In the modern age many people spend much of their time sitting. They sit at a desk working on a computer, sit on a couch watching TV, sit and read, etc. Consequently, a device that provides exercise while seated is desirable. Ideally, such a device does not unduly distract the user from a primary activity, e.g., working, watching, reading, etc.
One commercially-available device for providing exercise while seated is a pedal exerciser. These devices are basically just the pedals and resistance mechanism of an exercise bicycle without the frame, seat, handle bars, etc. Consequently, the device is usually used by placing it on the floor at the user's feet while they sit on standalone seating. Changing the resistance of a pedal exerciser, however, generally requires a conscious effort by the user. For instance, it may involve turning a knob, pushing “up” or “down” buttons, etc. Alternatively, pedal exercisers that use an electromagnetic resistance mechanism may be programmable. The disadvantage to such an arrangement is that changes in the resistance level may be out of synch with the user's fatigue level.
Furthermore, a pedal exerciser generally provides resistance only while pushing out against the pedals. Consequently, the device primarily exercises only the user's quadriceps and related muscles.
Another result of this arrangement is that using a pedal exerciser usually requires the user to push against a standalone seat with their back. Consequently, using a pedal exerciser, particularly with any sort of vigor, can cause the seat and/or the exerciser to move around. This is particularly problematic for rolling chairs. Also, because the user applies force to the pedals towards the top of each stroke, the exerciser can be unstable. These issues can be mitigated somewhat by using more of a downward (as opposed to outward) force on the pedals. However, this is a somewhat unnatural motion.
In addition, using a pedal exerciser causes considerable vertical movement of the knees. Consequently, although they are often marketed as a way to stay active while seated at a desk or table, pedal exercisers can be awkward, difficult, and sometimes impossible to use under such circumstances.
In addition, pedal exercisers are fairly large and bulky. Consequently, if left under a desk or table when not in use, a pedal exerciser will tend to get in the way of a person's feet and legs during normal desk use. Their bulk can also make them inconvenient to store, transport, etc.
Miniature elliptical trainers are also marketed as a way to exercise while sitting on standalone seating. The primary advantage of a “mini” elliptical trainer over a pedal exerciser is the reduced up and down movement of the knees. This assumes the trainer is used with balls of the feet over the cranks (opposite the way it's normally used when standing up). Even then, however, the heels are at or near the height of the crank axle which can still cause knee clearance issues when using the trainer while seated at a table or desk.
Also, because of the combination of cranks and generally horizontal foot platforms, mini-elliptical trainers tend to encourage more of a downward (as opposed to outward) force. As mentioned above, this can somewhat mitigate push back against the seat and instability of the trainer. However, it's similarly a somewhat unnatural motion. In addition, a mini elliptical trainer still has the resistance and bulk issues discussed above.
There have been recent attempts to address some of the above shortcomings. For instance, U.S. Published Patent Application No. 2001/0036885 for a “Compact Shuffle Leg Exerciser” describes two platforms, one for each foot, riding on parallel rails within a frame. The user then sits on a standalone seat and with their feet on the platforms moves their feet and lower legs back and forth in a scissor-type motion. This eliminates the up-and-down movement of the knees and significantly reduces the bulk of the device. However, the device described still has some shortcomings.
In the application referenced above, one of the ways resistance to movement of the foot platforms is provided is by a screw-type mechanism that increases the friction between the platforms and the rails. As with pedal and elliptical exercisers of a non-programmable variety, this requires manual adjustment of the resistance. It also can cause considerable wear and tear on the device.
Furthermore, the force to move the foot platforms forward and backward results in an equal but opposing force against the user's seat. As with pedal and elliptical exercisers, these opposing forces tend to cause the seat and/or exercise device to move around during use.
The application referenced above also provides for resistance to movement of the foot platforms by connecting them to the frame via elastic elements (see FIG. 14 of the application referenced above). However, because the frame is anchoring the elastic elements, this arrangement has the same tendency to cause the seat and/or exercise device to move around during use.
In addition, to allow for sufficient travel of the foot platforms, the elastic elements must have a fairly long relaxed length. This is also important to maximize the longevity of the elastic elements. Consequently, the device must be sized or otherwise designed to accommodate this length, though this issue isn't addressed in the above application.
Furthermore, the elastic elements connecting the foot platforms to the frame run in a lengthwise direction, i.e. parallel with the rails. Consequently, the force they exert in a lengthwise direction tends to increase and decrease at a steady rate. This isn't an issue when pushing or pulling only, i.e. when only working against elastic elements connected to one end or the other of the frame. However, moving one's feet and lower legs back and forth in a scissor-type motion involves repeatedly alternating between pushing against one set of elastic elements, i.e. those connecting the foot platforms to the end of the device closest to the user, then having those same elements pull one's feet and lower legs back toward the middle of the device, immediately followed by pulling against another set of elastic elements, i.e. those connecting the platforms to the end of the device furthest from the user, then having those same elements pull one's feet forward toward the middle of the device. Consequently, having the force exerted by the elastic elements increase and decrease at a steady rate tends to lead to an uneven motion as the user scissors their feet and lower legs back and forth.
U.S. Pat. No. 8,500,611 for a “Dual Track Exercise Device” describes a device that's similar in construction to that described in U.S. Published Patent Application No. 2001/0036885. However, it's larger in size and generally geared more towards a range of targeted exercises. This device is marketed by Balanced Body, Inc. as the CoreAlign.
U.S. Pat. No. 7,951,050 for an “Apparatus for Aerobic Leg Exercise of a Seated User” describes a device that's also similar in construction to that described in U.S. Published Patent Application No. 2001/0036885. However, it eschews any type of resistance mechanism. Rather, it is designed for “non-resistive movement” as opposed to exercise per se.
U.S. Pat. No. 5,807,212 for a “Leg Exerciser Particularly Adapted for Use Under Desks” describes a device with “pedals” configured to move in a linear fashion. Various mechanisms oriented parallel to the movement of the pedals are proposed to provide resistance. However, because of this orientation, the resistance increases in a rather steep linear fashion. Furthermore, the device provides resistance only while pushing out against the pedals. Consequently, the device exercises only the quadriceps and related muscles. Among other things, this focus on the quadriceps causes particularly pronounced pushback against the seat. The patent referenced above addresses this drawback by including an anchor system to connect the user's chair to the exercise device. The anchor system also helps mitigate any instability caused by having the pedals well above the base. However, this adds to the expense and bulk of the device. It also makes set-up of the device more elaborate, thereby making the device less convenient to move from place to place.